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Ad-Hoc and Sensor networks Symposium

作者： Kun Chen Xiangming Wen Wenpeng Jing Zhaoming Lu Hua Shao Heng Xu Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications

ISBN: (纸本)9781479966653

Energy harvesting from ambient radio frequency (RF) radiation is an efficient approach to provide wireless energy replenishment for mobile devices. At the same time, introducing active/sleep modes in base stations (BSs) is an effective method to save the energy consumption of cellular networks. However, the performance of the two techniques would be dependent and interact with each other if both of them were employed in cellular networks. In this paper, we analyze the performance and investigate the sleeping strategy design problem in the cellular network, in which the mobile devices have the capability of energy harvesting from the ambient RF signals. Specifically, using tools from stochastic geometry theory, we derive analytical expressions of the coverage probability and the harvested energy and show that they are both affected by the sleeping strategy. Then, we formulate a BSs power consumption minimization problem under the coverage probability and harvesting performance constraints. Finally, the optimal operating regime of the sleeping strategy is derived. Numerical results confirm the correctness of the analysis and show the effect of switching off BSs on both performance metrics.

关键词： RF energy harvesting Energy efficiency Sleep control Stochastic geometry Poisson point process

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Energy Efficiency Optimization in OFDMA Heterogeneous networks with RF Energy Harvesting

Energy Efficiency Optimization in OFDMA Heterogeneous Networ...

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IEEE Annual International Symposium on Personal, Indoor, and Mobile Radio Communications

作者： Zhiqiang Chen Xiangming Wen Zhaoming Lu Wenpeng Jing Zeguo Xi Kun Chen Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications

ISBN: (纸本)9781509032556

In this paper, the power allocation problem, which aims to optimize the energy efficiency (EE) of downlink OFDMA heterogeneous networks, is researched. Specifically, the terminals are sensor nodes in the Internet of Things (IoT) with RF energy harvesting (EH) technology. This technology enables the sensor nodes to capture energy from the wireless signals in air, constitutes a permanent energy source, and provides self-stainability to them. Traditional interference analysis and EE modeling are unsuitable for our EH introduced problem, so we model the energy-efficient power allocation problem as an EH based non-cooperative (EHNC) game. Then we prove the existence and reveal the uniqueness conditions of the EHNC game equilibrium. We propose a distributed energy-efficient power allocation algorithm to solve the problem, and reveal that the game can converge to Nash equilibrium after certain times of iterations. Simulation results show that the proposed algorithm is effective in increasing energy-efficient performance, harvesting energy and guaranteeing QoS of the IoT sensor nodes simultaneously.

关键词： Energy efficiency RF energy OFFICE OF THE ASSISTANT SECRETARY FOR ENVIRONMENT, ET. AL. power splitting Heterogeneous networks Energy sources energy harvesting Game theory Game animals OFDMA harvesting Nash equilibrium Hunting

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Transmission Opportunity of Spectrum Sharing with Cellular Uplink Spectrum in Cognitive VANET

Transmission Opportunity of Spectrum Sharing with Cellular U...

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IEEE Vehicular Technology Conference

作者： Hang Zhang Xinxin He Tao Luo Weisen Shi Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications

ISBN: (纸本)9781509016990

In this paper, we propose a cellular cognitive-radio vehicular ad hoc network (CCR-VANET) which consists of cellular network (primary network) and vehicular ad hoc network (secondary network). The two coexisting networks share the uplink spectrum of cellular network. The moving pattern of all vehicles is described as the classic Car-Following model. A cognitive carrier sense multiple access with collision avoidance (cognitive-CSMA) protocol with two-stage decision is investigated to opportunistically access the uplink spectrum. Based on this model and protocol, the transmission opportunity is derived by using stochastic geometry tools. Finally, simulation results show that, with cognitive-CSMA protocol and invariable transmission power of coexisting networks, the CCR-VANET transmission opportunity increases with the increasing of maximum received beacon power threshold, predefined carrier sensing threshold and the number of subchannels, while decreases with the increasing of the density of active primary transmitters.

关键词： Cognitive radio VANET CSMA/CA Car-Following model Transmission opportunity Carrier Sense Multiple Access / Collision Avoidance Cognitive radio up link V2V Ad hoc networks Spectra Collision avoidance Cells subchannel power transmission transmission

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On stochastic geometry analysis of dense WLAN with dynamic carrier sense threshold and rate control

On stochastic geometry analysis of dense WLAN with dynamic c...

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International Symposium on Wireless Personal Multimedia Communications (WPMC)

作者： Xiaoguang Zhao Xiangming Wen Tao Lei Zhaoming Lu Biao Zhang Beijing Key Laboratory of Network System Architecture and Convergence Beijing Beijing Laboratory of Advanced Information Networks Beijing

ISBN: (纸本)9781509053773

Recently, wireless local area networks (WLANs) have been densely deployed. In high density WLANs, co-channel interference has become one of the biggest challenges for the network performance. The IEEE 802.11 based WLANs have limited wireless channels, therefore, not all the adjacent APs can work in different non-overlapping channels and co-channel interference will affect the network performance severely. To get better network performance, transmit power control scheme is used to reduce the co-channel interference from neighbour nodes. However, transmit power control scheme may cause asymmetric links, we propose a dynamic carrier sense and rate control (DCR) scheme to improve the network performance in dense WLANs. The DCR scheme mainly tunes the carrier sense threshold (CST) and rate for the edge stations (STAs). A stochastic geometry model is also demonstrated for the analysis of the network performance. The network performance is evaluated by the coverage probability. Then, we simulate the coverage probability of WLAN which uses the existing static carrier sense threshold scheme and the proposed DCR scheme. Simulation results show that the proposed DCR scheme yields better coverage probability compared with the existing static carrier sense threshold scheme.

关键词： Stochastic processes Geometry Wireless LAN IEEE 802.11 Standard Throughput Interchannel interference

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Structural Modeling and Characteristics Analysis of Flow Interaction networks in the Internet

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Chinese Physics Letters 2015年第6期32卷 204-207页

作者：武晓宇顾仁涛潘卓娅金伟祺纪越峰 Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications

Applying network duality and elastic mechanics, we investigate the interactions among Internet flows by con- structing a weighted undirected network, where the vertices and the edges represent the flows and the mutual dependence between flows, respectively. Based on the obtained flow interaction network, we find the existence of ＇super flow＇ in the Internet, indicating that some flows have a great impact on a huge number of other flows; moreover, one flow can spread its influence to another through a limited quantity of flows （less than 5 in the experimental simulations）, which shows strong small-world characteristics like the social network. To reflect the flow interactions in the physical network congestion evaluation, the ＇congestion coefficient＇ is proposed as a new metric which shows a finer observation on congestion than the eonventional one.

关键词： POLYMER networks ELASTIC analysis (Engineering) INTERNET content INTERNET domain names network analysis (Social sciences)

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A QoS-based multi-rate multicast scheme over heterogeneous cellular network

A QoS-based multi-rate multicast scheme over heterogeneous c...

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International Symposium on Wireless Communication systems (ISWCS)

作者： Tang Liu Hailun Xia Chunyan Feng Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing China

ISBN: (纸本)9781509020621

Wireless multimedia traffic has increased considerably in recent years, which puts forward higher demand on the capacity of existing network. Multicast, as a transmission strategy with high spectral efficiency, has not been widely studied in heterogeneous cellular network (HetNet). In this paper, we propose a QoS-based multi-rate multicast scheme over HetNet to effectively improve the system throughput while guaranteeing the quality of service (QoS) of the whole system. We formulate an expression of system throughput of the proposed multicast scheme and decouple it into three subproblems for its computational complexity, namely, user association (UA), subgroup formation (SF) and resource allocation (RA). In UA, we present a traffic-oriented access method based on reference signal receiving power (RSRP). In SF, the associated users are divided into several subgroups according to their channel state information (CSI) and the users in one subgroup are served with the same rate determinated by the CSI level of the subgroup. In RA, fractional frequency reuse (FFR) mechanism is used to eliminate the co-channel cross-tier interference between macro base station (MBS) and small base stations (SBS). And QoS is considered both in subcarrier allocation and power allocation processes. Simulation results show that the system throughput is significantly improved while QoS is guaranteed by using our scheme.

关键词： Resource management Quality of service Throughput Interference Computational complexity Base stations Wireless communication

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Modified Bayesian Inference for Trajectory Prediction of network Virtual Identity Based on Spark

Modified Bayesian Inference for Trajectory Prediction of Net...

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International Conference on Intelligent Human-Machine systems and Cybernetics, IHMSC

作者： Yuhang Song Gang He Dechen Yu Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing China

ISBN: (纸本)9781509007691

Traditional trajectory prediction method shows low prediction accuracy when dealing with a limited number of historical trajectory. Therefore an improved Bayesian inference (MBI) method is proposed, which builds a Markov model to quantify the correlation between adjacent locations, and provides a more accurate Markov model by decomposing the historical trajectory. Finally we improve Bayesian inference formula. The experiment uses Spark platform processing original data and intermediating results of calculations as the large amount of data to be calculated. The results show that, MBI method is 2-3 times faster than the speed of existing prediction methods, and has higher accuracy and stability. MBI method makes full use of existing track information, not only to improve the query efficiency, but also to ensure a higher prediction accuracy.

关键词： Trajectory Sparks Markov processes Bayes methods Databases History

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network traffic and user behavior analysis of mobile reading applications

Network traffic and user behavior analysis of mobile reading...

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International Conference on Information Science and Technology (ICIST)

作者： Yue Chang Fang Liu Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing China

Mobile reading ranks No.4 on the permeate proportion of the mobile Internet applications and is increasing gradually. Understanding user behaviors of mobile reading is important for service provider. However, few work has been done on reading analysis. In this paper, we provide an approach to solve this problem based on cloud computing platform including HDFS and Apache Pig. Our study is carried out based on the data collected from the ISP network which covered an entire city in southern China. We presented the feature of traffic and behavior in three aspects. First, we compared the service condition of several popular websites in mobile reading field and found the basic law that traffic distribution fits. Second, we recognize user sessions via time threshold method and found some interesting phenomenon about session duration. Finally, we break user actions down into discrete categories and summarized the characteristics of each reading application. We compared user acceptance of different applications from three perspectives, which are user loyalty, user behavior and cross-user distribution respectively.

关键词： Decision support systems Time-frequency analysis

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WoT/SDN:Web of Things architecture Using SDN

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China Communications 2015年第11期12卷 177-187页

作者： QIU Xiaofeng LIU Wenmao GAO Teng HE Xinxin WEN Xutao CHEN Pengcheng Beijing Key Laboratory of Network System Architecture and Convergence BUPT NSFocus Security Labs

Wo T(Web of Things) integrates smart devices into Web by reusing and extending Web standards. While Web technology makes the developers' job easier,it faces security,management and efficiency challenges. We propose Wo T/SDN,the architecture of resource oriented Wo T built on SDN(Software Defined network),in which applications could be developed through resource subscription and Mashup with the programmability provided by SDN. The key components are designed,including Security and Management Controller(SMC),various atomic services and resource subscription syntax. Three applications covering device management,data access and security protection are demonstrated. Compared to traditional resource-oriented Wo T systems,our test results show that SDN,with its logically centralized control capability and awareness of flow forwarding,provides new opportunity to improve performance,simplify management and enhance security for Wo T.

关键词： Wo T SDN Controller

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Where do you watch? A spatial analysis of online video service in mobile network

Where do you watch? A spatial analysis of online video servi...

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International Symposium on Wireless Personal Multimedia Communications (WPMC)

作者： Chenyu Li Jun Liu Shuxin Ouyang Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing China

ISBN: (纸本)9781509053773

We present a specialized characterization work in the spatial dimension of online video service in mobile network. A better understanding of the spatial characteristics of such service is a key capability for network operators and service providers, but remains an unsolved problem. It is extremely challenging because the complexity to get the location information of the mobile users. In this paper, we address this problem head on by collecting a large-scale dataset containing over 9 billion network traffic traces from a cellular network in a north-eastern city in China. We further extract the video requests from those data. The user location information is cast into the information of cells visited by the users in the cellular network when they watch mobile videos. Based on this dataset, we provide a comprehensive characterization of the online video service in mobile network in the spatial dimension: 1) The overall geographic distribution of video requests is uncovered and hot spot regions are discovered. And the video request location entropy is defined to analyze how request time and video category impact the overall geographic distribution. 2) Then, the user mobility pattern is defined in terms of cell sequence and residence time. The movement of each mobile user while watching videos in mobile network and the overlapping of request locations between different sessions and different days of each user are further studied. 3) At last, the video request spatial distribution of each video is analyzed. The linear relationship between the video request spatial distribution and the video popularity is uncovered. In addition, the categories and user mobility patterns for the widely watched videos are analyzed. To the best of our knowledge, this is the first specialized study to shed light on the online video service in mobile network from the spatial angle. Our analysis provides a unique insight into how Youku is utilized by mobile users. We believe our observation find

关键词： Mobile computing Streaming media YouTube Cellular networks Urban areas Entropy

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